Saltwater contamination of freshwater resources could make many atoll islands uninhabitable in decades

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Sea-level rise and wave-driven flooding could introduce saltwater so frequently into atoll islands’ freshwater resources that many will be uninhabitable by the mid-21st century, according to a new study published in Science Advances.

Cartoons showing ocean wave scenarios and what would happen to groundwater given rising sea level conditions.

Conceptual diagram showing impact of sea-level rise and wave-driven flooding on atoll-island groundwater. (A) Current sea level. (B) Future sea level. Sea-level rise will allow for greater wave heights (H) and wave-driven runup (R), resulting in frequent overwash that will contaminate the atoll island’s freshwater lens. Note: Heights are exaggerated. From article by Storlazzi and others, Science Advances 4:4, published April 25, 2018.

Scientists from the U.S. Geological SurveyDeltaresNational Oceanic and Atmospheric Administration, and the University of Hawaiʻi at Mānoa focused fieldwork and model development on Roi-Namur Island on Kwajalein Atoll in the Republic of the Marshall Islands for this study. Researchers used several climate-change scenarios prescribed by the U.S. Department of Defense to project the impact of sea-level rise and wave-driven flooding on infrastructure and freshwater availability. Their findings can be applied to atolls around the world, most of which have, on average, even lower land elevations than Roi-Namur. The Department of Defense provided partial funding for the study and received results in an earlier report.